Gas generator

Abstract

To provide a gas generator capable of suppressing an increase in mass of a housing.SOLUTION: A disk type gas generator 100 includes: a housing having a lower shell 10 and an upper shell 20 and storing therein a gas generating agent 61 that generates gas by combustion; and an igniter 40 for igniting and burning the gas generating agent 61. The lower shell 10 has: a bottom plate part 11; and a cylindrical peripheral wall part 12 extending from an outer peripheral edge part of the bottom plate part 11 toward the upper shell 20 side. The bottom plate part 11 has: a flat plate part 16 provided in the periphery of a center part of the bottom plate part 11; and a protrusive cylindrical part 13 having a curved part 17 curved so as to be located further in the upper shell 20 side as going closer to the inward side from an inner peripheral edge part of the flat plate part 16, the protrusive cylindrical part 13 projecting toward the upper shell 20 side in the center part of the bottom plate part 11. A thickness of the flat plate part 16 and the curved part 17 is equal to or greater than 1.1 times a thickness other than the flat plate part 16 and the curved part 17 in the lower side shell 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a gas generator incorporated in an occupant protection device for protecting an occupant in the event of a vehicle collision, and more particularly to a gas generator incorporated in an airbag device mounted on an automobile or the like. [Background technology]

[0002] Airbag devices, which are passenger protection devices, have become widespread from the viewpoint of protecting passengers in automobiles, etc. Airbag devices are installed to protect passengers from impacts that occur during a vehicle collision, and the airbag instantly inflates and deploys during a vehicle collision, thereby acting as a cushion to support the passenger's body.

[0003] Gas generators have a variety of structures, but a gas generator that is particularly suitable for use in a driver's side airbag device, a passenger's side airbag device, etc. is a short, approximately cylindrical disk-type gas generator with a relatively large outer diameter.

[0004] A disk-type gas generator has a short, approximately cylindrical housing with both axial ends closed, a plurality of gas outlets provided in the peripheral wall of the housing, a transfer charge contained inside the housing so as to face an igniter assembled to the housing, a gas generating agent filled inside the housing so as to surround the transfer charge, and a filter contained inside the housing so as to further surround the gas generating agent.

[0005] For example, Patent Document 1 discloses a cylindrical airbag inflator container that includes a container body, a lid, and a central fixing part that is integrated into the center of the container body and lid and has a space for accommodating ignition means. At least a portion of the outer circumferential surface of the central fixing part is thickened. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 5-16762 Summary of the Invention [Problem to be solved by the invention]

[0007] It is desirable to prevent the mass of the housing from increasing, but if the thickness of the housing is made too thin in order to reduce the mass of the housing, there is a risk that the housing will break when the gas generator is activated.

[0008] Therefore, the present invention has been made in consideration of the above circumstances, and has an object to provide a gas generator that can suppress breakage of the housing while suppressing an increase in the mass of the housing. [Means for solving the problem]

[0009] (1) A gas generator of the present invention comprises a housing having a lower shell and an upper shell, and containing a gas generating agent that generates gas by combustion, and an igniter that ignites and burns the gas generating agent, wherein the lower shell has a bottom plate portion and a cylindrical peripheral wall portion extending from the outer peripheral edge of the bottom plate portion toward the upper shell side, and the bottom plate portion has a flat plate portion provided around the center of the bottom plate portion and a curved portion that curves inward from the inner peripheral edge of the flat plate portion to be positioned toward the upper shell side, and a tubular portion that protrudes from the center of the bottom plate portion toward the upper shell side, and wherein the thicknesses of the flat plate portion and the curved portion are 1.1 times or more the thickness of the parts of the lower shell other than the flat plate portion and the curved portion.

[0010] (2) A gas generator of the present invention comprises a housing having a lower shell and an upper shell, containing a gas generating agent therein that generates gas by combustion, and an igniter that ignites and burns the gas generating agent, wherein the lower shell has a bottom plate portion and a cylindrical peripheral wall portion that extends from the outer peripheral edge of the bottom plate portion toward the upper shell, and the maximum thickness of the lower shell is 1.2 times or more the minimum thickness of the lower shell.

[0011] (3) A gas generator of the present invention comprises a housing having a lower shell and an upper shell, and containing a gas generating agent that generates gas by combustion, and an igniter that ignites and burns the gas generating agent, wherein the lower shell has a bottom plate portion and a cylindrical peripheral wall portion extending from the outer peripheral edge of the bottom plate portion toward the upper shell side, and the bottom plate portion has a flat plate portion provided around the center of the bottom plate portion and a curved portion that curves inward from the inner peripheral edge of the flat plate portion to be positioned toward the upper shell side, and a cylindrical portion that protrudes from the center of the bottom plate portion toward the upper shell side, and the thicknesses of the flat plate portion and the curved portion are greater by 0.2 mm or more than the thickness of parts of the lower shell other than the flat plate portion and the curved portion.

[0012] (4) A gas generator of the present invention comprises a housing having a lower shell and an upper shell, containing a gas generating agent inside that generates gas by combustion, and an igniter that ignites and burns the gas generating agent, wherein the lower shell has a bottom plate portion and a cylindrical peripheral wall portion extending from the outer peripheral edge of the bottom plate portion toward the upper shell side, and wherein the maximum thickness of the lower shell is 1.1 mm or more and the minimum thickness of the lower shell is 0.9 mm or less.

[0013] (5) A gas generator of the present invention has a lower shell and an upper shell, a housing that contains a gas generating agent that generates gas when burned, and an igniter that ignites and burns the gas generating agent, wherein the lower shell has a bottom plate portion and a cylindrical peripheral wall portion that extends from the outer peripheral edge of the bottom plate portion toward the upper shell, and the bottom plate portion has a flat plate portion that is provided around the center of the bottom plate portion and a curved portion that curves inward from the inner peripheral edge of the flat plate portion to be positioned toward the upper shell, and the cylindrical portion that protrudes from the center of the bottom plate portion toward the upper shell, and the upper shell has a top plate portion and a cylindrical peripheral wall portion that extends from the outer peripheral edge of the top plate portion toward the lower shell, and the thickness of the top plate portion is 0.9 times or more the thicknesses of the flat plate portion and the curved portion.

[0014] (6) A gas generator of the present invention comprises a housing having a lower shell and an upper shell, containing a gas generating agent inside that generates gas when burned, and an igniter that ignites and burns the gas generating agent, wherein the lower shell has a bottom plate portion and a cylindrical peripheral wall portion extending from the outer peripheral edge of the bottom plate portion toward the upper shell, and the upper shell has a top plate portion and a cylindrical peripheral wall portion extending from the outer peripheral edge of the top plate portion toward the lower shell, and the difference between the maximum thickness of the lower shell and the maximum thickness of the upper shell is 0.1 mm or less.

[0015] (7) In the gas generators described above in (1) to (6), the material forming the lower shell and the material forming the upper shell preferably have a tensile strength of 780 MPa or more.

[0016] (8) From another viewpoint, in the gas generators described above in (1) to (6), the mass of the lower shell may be 80 g or less.

[0017] (9) From another viewpoint, in the gas generators described above in (1) to (6), the mass of the upper shell may be 62 g or less.

[0018] (10) From another viewpoint, in the gas generators described above in (1) to (6), the lower shell and the upper shell may have a total mass of 142 g or less. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a gas generator that can prevent the mass of the housing from increasing. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a schematic cross-sectional view showing a disk-type gas generator according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic plan view showing the disk-type gas generator of FIG. 1. [Figure 3] 2 is a schematic enlarged cross-sectional view showing a part of the housing of the disk-type gas generator of FIG. 1. FIG. [Figure 4] 2 is a schematic cross-sectional view showing a housing and the like of the disk-type gas generator of FIG. 1 in a state where the internal pressure is not rising. FIG. [Figure 5] 2 is a schematic cross-sectional view showing a housing and the like of the disk-type gas generator of FIG. 1 in a state where the internal pressure is increased. FIG. [Figure 6] 2 is a graph showing the hydropressure applied to the lower shell of the disk-type gas generator of FIG. 1. [Figure 7] 2 is a graph showing the hydropressure applied to the upper shell of the disk-type gas generator of FIG. 1. [Figure 8] 10 is a graph showing the relationship between the thickness of a flat plate portion in a lower shell of a disk-type gas generator and the rupture pressure of the lower shell. [Figure 9] 10 is a graph showing the relationship between the thickness of a curved portion in a lower shell of a disk-type gas generator and the rupture pressure of the lower shell. DETAILED DESCRIPTION OF THE INVENTION

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiments shown below, the present invention is applied to a disc-type gas generator that is suitably incorporated into an airbag device mounted on the steering wheel of an automobile, etc. In the embodiments shown below, identical or common parts are designated by the same reference numerals in the drawings, and their description will not be repeated.

[0022] FIG. 1 is a schematic cross-sectional view showing a disk-shaped gas generator 100 according to an embodiment of the present invention. FIG. 2 is a schematic plan view showing disk-shaped gas generator 100 of FIG. 1. FIG. 3 is a schematic enlarged cross-sectional view showing a part of the housing of disk-shaped gas generator 100 of FIG. 1. In FIG. 3, the boundary between the flat plate-like portion and the curved plate-like portion is indicated by a dashed line. FIG. 4 is a schematic cross-sectional view showing the housing etc. of disk-shaped gas generator 100 of FIG. 1 in a state where the internal pressure has not increased. FIG. 5 is a schematic cross-sectional view showing the housing etc. of disk-shaped gas generator 100 of FIG. 1 in a state where the internal pressure has increased. First, with reference to FIGS. 1 to 5, disk-shaped gas generator 100 according to the present embodiment will be described.

[0023] 1, disk-shaped gas generator 100 includes a housing, holding portion 30, igniter 40, cup-shaped member 50, lower support member 70, upper support member 80, cushion material 85, and filter 90. An accommodating space provided inside the housing accommodates internal components such as a part of holding portion 30, igniter 40, cup-shaped member 50, transfer charge 59, gas generating agent 61, lower support member 70, upper support member 80, cushion material 85, and filter 90. A combustion chamber 60 is located in the accommodating space provided inside the housing and mainly accommodates gas generating agent 61, one of the above-mentioned internal components.

[0024] The housing is a short, generally cylindrical body with one axial end and the other axial end closed. The housing includes a lower shell 10 and an upper shell 20. The lower shell 10 and the upper shell 20 are each formed as a press-molded product, for example, by pressing a rolled metal plate-like member. The metal plate-like members constituting the lower shell 10 and the upper shell 20 are made of metal plates made of stainless steel, iron steel, aluminum alloy, stainless alloy, or the like, and preferably so-called high-tensile steel plates that will not break or otherwise be damaged even when a tensile stress of 440 MPa or more is applied.

[0025] The lower shell 10 and the upper shell 20 are each formed in a generally cylindrical shape with a bottom, and are assembled and joined together with their open surfaces facing each other to form a housing. The lower shell 10 has a bottom plate 11 and a peripheral wall 12, while the upper shell 20 has a top plate 21, a peripheral wall 22, and a flange 25. The peripheral wall 12 extends from the outer periphery of the bottom plate 11 toward the upper shell 20. The peripheral wall 22 extends from the outer periphery of the top plate 21 toward the lower shell 10.

[0026] The upper end of the peripheral wall 12 of the lower shell 10 is inserted into the lower end of the peripheral wall 22 of the upper shell 20 and press-fitted. Furthermore, the peripheral wall 12 of the lower shell 10 and the peripheral wall 22 of the upper shell 20 are joined at or near their abutment, thereby fixing the lower shell 10 and the upper shell 20 together. Here, electron beam welding, laser welding, friction welding, or the like can be suitably used to join the lower shell 10 and the upper shell 20 together.

[0027] As a result, the portion of the peripheral wall of the housing closer to the bottom plate 11 is formed by the peripheral wall 12 of the lower shell 10, and the portion of the peripheral wall of the housing closer to the top plate 21 is formed by the peripheral wall 22 of the upper shell 20. One end and the other end in the axial direction of the housing are closed by the bottom plate 11 of the lower shell 10 and the top plate 21 of the upper shell 20, respectively.

[0028] The bottom plate portion 11 of the lower shell 10 has a protruding tubular portion 13, a recessed portion 14, an opening 15, and a flat plate portion 16. The protruding tubular portion 13 protruding toward the top plate portion 21 is provided in the center of the bottom plate portion 11 of the lower shell 10, thereby forming a recessed portion 14 in the center of the bottom plate portion 11 of the lower shell 10. The protruding tubular portion 13 is a portion where the igniter 40 is fixed via the holding portion 30, and the recessed portion 14 is a portion that provides space for providing the female connector portion 34 in the holding portion 30. The recessed portion 14 is recessed toward the inside of the housing on the outer surface of the housing. Specifically, the recessed portion 14 is recessed toward the top plate portion 21 on the outer surface of the bottom plate portion 11.

[0029] Protruding tube portion 13 is formed in a generally cylindrical shape with a bottom, and an opening 15 having a point-asymmetric shape (for example, a D-shape, a barrel shape, an oval shape, etc.) in a plan view is provided at its axial end portion located on the top plate portion 21 side. Opening 15 penetrates bottom plate portion 11 in the axial direction. That is, opening 15 is formed at the bottom of recessed portion 14, penetrates bottom plate portion 11 in the direction in which recessed portion 14 is recessed, and communicates between the inside and outside of the housing. Opening 15 is a portion through which a pair of terminal pins 42 of igniter 40 are inserted.

[0030] The flat plate portion 16 is provided around the center of the bottom plate portion 11. In other words, the flat plate portion 16 is provided around the protruding tubular portion 13 and is annular. The flat plate portion 16 is flat, and the thickness direction of the flat plate portion 16 substantially coincides with the protruding direction of the protruding tubular portion 13. The protruding tubular portion 13 protrudes toward the upper shell 20 at the center of the bottom plate portion 11. The protruding tubular portion 13 protrudes from the inner peripheral edge of the flat plate portion 16 toward the upper shell 20 and is provided in an annular shape along the inner peripheral edge of the flat plate portion 16. The protruding tubular portion 13 has a curved portion 17 that curves inward from the inner peripheral edge of the flat plate portion 16 so as to be positioned toward the upper shell 20. The curved portion 17 is provided in an annular shape along the inner peripheral edge of the flat plate portion 16.

[0031] The igniter 40 is for generating a flame and includes an ignition portion 41 and a pair of terminal pins 42. The igniter 40 ignites and burns the gas generating agent 61. The ignition portion 41 is disposed inside the housing and is ignited by the flow of electric current. The ignition portion 41 includes an ignition charge that ignites and burns to generate a flame when activated, and a resistor for igniting the ignition charge. The pair of terminal pins 42 are a pair of terminal pins for passing electric current through the ignition portion 41. The pair of terminal pins 42 are connected to the ignition portion 41 to ignite the ignition charge. The pair of terminal pins 42 extend to the outside of the housing through the opening 15.

[0032] More specifically, the ignition unit 41 comprises a cup-shaped squib cup and a plug that closes the open end of the squib cup and through which a pair of terminal pins 42 are inserted and held; a resistor (bridge wire) is attached to connect the tips of the pair of terminal pins 42 inserted into the squib cup; and an ignition charge is loaded into the squib cup so as to surround or be close to the resistor.

[0033] Here, nichrome wire is generally used as the resistor, and ZPP (zirconium potassium perchlorate), ZWPP (zirconium tungsten potassium perchlorate), lead tricinate, etc. are generally used as the ignition charge. The squib cup and plug mentioned above are generally made of metal or plastic.

[0034] When a collision is detected, a predetermined amount of current flows through the resistor via the terminal pin 42. This current flow generates Joule heat in the resistor, causing the ignition charge to begin burning. The high-temperature flame generated by the combustion ruptures the squib cup containing the ignition charge. The time from when the current flows through the resistor to when the igniter 40 is activated is generally 2 ms or less when nichrome wire is used for the resistor.

[0035] Igniter 40 is attached to bottom plate 11 in a state where it is inserted from the inside of lower shell 10 so that terminal pin 42 passes through opening 15 provided in protruding cylindrical portion 13. Specifically, holding portion 30 made of a resin molded portion is provided around protruding cylindrical portion 13 provided on bottom plate 11, and igniter 40 is fixed to bottom plate 11 by being held by holding portion 30.

[0036] The retaining portion 30 is formed by injection molding (more specifically, insert molding) using a mold, and is formed by adhering an insulating fluid resin material to the bottom plate portion 11 of the lower shell 10 so that it passes through an opening 15 provided in the bottom plate portion 11 and reaches from a portion of the inner surface of the bottom plate portion 11 to a portion of the outer surface, and then solidifying it.

[0037] As the raw material for the holding portion 30 formed by injection molding, a resin material that exhibits excellent heat resistance, durability, corrosion resistance, and the like after hardening is preferably selected and used. In this case, it is not limited to thermosetting resins such as epoxy resin, but thermoplastic resins such as polybutylene terephthalate resin, polyethylene terephthalate resin, polyamide resin (e.g., nylon 6, nylon 66, etc.), polypropylene sulfide resin, and polypropylene oxide resin can also be used. When such a thermoplastic resin is selected as the raw material, it is preferable to incorporate glass fiber or the like as a filler into the resin material to ensure the mechanical strength of the holding portion 30 after molding. However, if sufficient mechanical strength can be ensured with the thermoplastic resin alone, it is not necessary to add the filler described above.

[0038] The retaining portion 30 has an inner covering portion 31 that covers part of the inner surface of the bottom plate portion 11 of the lower shell 10, an outer covering portion 32 that covers part of the outer surface of the bottom plate portion 11 of the lower shell 10, and a connecting portion 33 that is located within the opening 15 provided in the bottom plate portion 11 of the lower shell 10 and is continuous with the inner covering portion 31 and the outer covering portion 32, respectively.

[0039] The retaining portion 30 is fixed to the bottom plate portion 11 on the surfaces of the inner covering portion 31, the outer covering portion 32, and the connecting portion 33 that face the bottom plate portion 11. The retaining portion 30 is also fixed to the side and bottom surfaces of the ignition portion 41 of the igniter 40 near the lower end, and to the surface of the terminal pin 42 of the igniter 40 near the upper end.

[0040] As a result, opening 15 is completely filled with terminal pin 42 and holding portion 30, and the sealing of this portion ensures airtightness of the space inside the housing. Since opening 15 is formed in an asymmetrical shape in a plan view as described above, by filling opening 15 with connecting portion 33, opening 15 and connecting portion 33 also function as an anti-rotation mechanism that prevents holding portion 30 from rotating relative to bottom plate portion 11.

[0041] The outer covering portion 32 of the holding portion 30 is embedded in the recessed portion 14, recessed toward the interior of the housing, and open toward the opposite side of the interior of the housing. Specifically, the outer covering portion 32 of the holding portion 30 is recessed toward the top plate portion 21, and open toward the opposite side of the top plate portion 21. The holding portion 30 holds the igniter 40 with a pair of terminal pins 42 exposed from the bottom of the outer covering portion 32. The pair of terminal pins 42 protrude from the bottom of the outer covering portion 32.

[0042] A female connector portion 34 is formed on the portion of the outer covering portion 32 of the holding portion 30 facing the outside. The female connector portion 34 is a portion for receiving a male connector (not shown) of a harness for connecting the igniter 40 to a control unit (not shown), and is located in a recess 14 provided in the bottom plate portion 11 of the lower shell 10.

[0043] A portion of the terminal pin 42 of the igniter 40 near the lower end is exposed and disposed within the female connector portion 34. A male connector is inserted into the female connector portion 34, thereby establishing electrical continuity between the core wire of the harness and the terminal pin 42.

[0044] The above-described injection molding may also be performed using a lower shell 10 in which an adhesive layer is provided in advance at a predetermined position on the surface of the bottom plate portion 11 in the portion that will be covered by the holding portion 30. The adhesive layer can be formed by applying adhesive to a predetermined position on the bottom plate portion 11 in advance and then curing the adhesive.

[0045] In this way, the hardened adhesive layer is positioned between the bottom plate portion 11 and the holding portion 30, so that the holding portion 30, which is made of a resin molded portion, can be more firmly fixed to the bottom plate portion 11. Therefore, if the adhesive layer is provided in a ring shape along the circumferential direction so as to surround the opening 15 provided in the bottom plate portion 11, it is possible to ensure higher sealing performance in that portion.

[0046] Here, the adhesive to be applied in advance to the bottom plate portion 11 is preferably one containing as a raw material a resin material that has excellent heat resistance, durability, corrosion resistance, etc. after hardening, and is particularly preferably one containing as a raw material a cyanoacrylate resin or a silicone resin. In addition to the above-mentioned resin materials, materials containing raw materials such as phenolic resins, epoxy resins, melamine resins, urea resins, polyester resins, alkyd resins, polyurethane resins, polyimide resins, polyethylene resins, polypropylene resins, polyvinyl chloride resins, polystyrene resins, polyvinyl acetate resins, polytetrafluoroethylene resins, acrylonitrile butadiene styrene resins, acrylonitrile styrene resins, acrylic resins, polyamide resins, polyacetal resins, polycarbonate resins, polyphenylene ether resins, polybutylene terephthalate resins, polyethylene terephthalate resins, polyolefin resins, polyphenylene sulfide resins, polysulfone resins, polyethersulfone resins, polyarylate resins, polyetheretherketone resins, polyamideimide resins, liquid crystal polymers, styrene rubbers, and olefin rubbers can also be used as the above-mentioned adhesives.

[0047] Here, an example of a configuration has been given in which the igniter 40 can be fixed to the lower shell 10 by injection molding the retaining portion 30 made of a resin molded portion, but other alternative means can also be used to fix the igniter 40 to the lower shell 10.

[0048] A cup-shaped member 50 is attached to the bottom plate 11 so as to cover the protruding tube 13, the holding portion 30, and the igniter 40. The cup-shaped member 50 has a generally cylindrical shape with a bottom that is open at the end on the bottom plate 11 side, and includes a space therein for accommodating a transfer charge 59. The cup-shaped member 50 is positioned so that it protrudes into the combustion chamber 60 that accommodates the gas generating agent 61, with the space provided therein facing the ignition portion 41 of the igniter 40.

[0049] The cup-shaped member 50 has a top wall portion 51, a cylindrical side wall portion 52 extending from the periphery of the top wall portion 51 toward the bottom plate portion 11, and an extension portion 53 extending radially outward from the opening end, which is the end of the side wall portion 52 on the bottom plate portion 11 side.

[0050] The extension portion 53 is formed to extend along the inner surface of the bottom plate portion 11 of the lower shell 10. Specifically, the extension portion 53 has a curved shape to follow the shape of the inner bottom surface of the bottom plate portion 11 at and near the portion where the protruding tubular portion 13 is provided, and includes a tip portion 54 extending in a flange shape at its radially outer portion.

[0051] The tip 54 of the extension 53 is disposed between the bottom plate 11 and the lower support member 70 along the axial direction of the housing, and is thereby sandwiched between the bottom plate 11 and the lower support member 70 along the axial direction of the housing. As a result, the tip 54 of the extension 53 of the cup-shaped member 50 is pressed toward the bottom plate 11 by the lower support member 70, and the cup-shaped member 50 is fixed to the bottom plate 11. This prevents the cup-shaped member 50 from falling off the bottom plate 11 without using crimping or press-fitting to fix the cup-shaped member 50.

[0052] Cup-shaped member 50 has no openings in either side wall 52 or top wall 51, and surrounds an internal space. When transfer charge 59 in transfer chamber 57 is ignited by activation of igniter 40, cup-shaped member 50 bursts, deforms, or melts due to an increase in pressure in the internal space and conduction of the generated heat.

[0053] Suitable materials for the cup-shaped member 50 include metal members such as stainless steel, steel, aluminum, aluminum alloy, stainless steel, stainless steel alloy, etc., and resin members such as thermosetting resins typified by epoxy resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyamide resin (e.g., nylon 6, nylon 66, etc.), polypropylene sulfide resin, polypropylene oxide resin, etc. In particular, aluminum alloys or iron-based metal materials such as stainless steel and steel, which have relatively higher mechanical strength than aluminum, are preferred.

[0054] The method for fixing the cup-shaped member 50 is not limited to the above-described fixing method using the lower support member 70, and other fixing methods may be used.

[0055] The transfer charge 59 filled in the transfer chamber 57 is ignited by the flame generated by the activation of the igniter 40, and generates thermal particles as it burns. The transfer charge 59 must be capable of reliably starting the combustion of the gas generant 61, and generally, a composition made of a metal powder / oxidizer, such as B / KNO3, B / NaNO3, or Sr(NO3)2, a composition made of titanium hydride / potassium perchlorate, or a composition made of B / 5-aminotetrazole / potassium nitrate / molybdenum trioxide, is used.

[0056] The enhancer charge 59 may be in a powder form, or may be formed into a predetermined shape using a binder. The enhancer charge 59 formed using a binder may have various shapes, such as granules, cylinders, sheets, spheres, single-hole cylinders, multi-hole cylinders, tablets, and the like.

[0057] Within the space inside the housing, a combustion chamber 60 containing a gas generating agent 61 is located in the space surrounding the portion in which the cup-shaped member 50 is disposed. Specifically, as described above, the cup-shaped member 50 is disposed so as to protrude into the combustion chamber 60 formed inside the housing, and the space provided in the portion facing the outer surface of the top wall portion 51 of the cup-shaped member 50 and the space provided in the portion facing the outer surface of the side wall portion 52 form the combustion chamber 60. As a result, the gas generating agent 61 is disposed adjacent to the outer surface of the cup-shaped member 50.

[0058] Furthermore, a filter 90 is disposed along the inner periphery of the housing in the space that radially surrounds the combustion chamber 60 that accommodates the gas generating agent 61. The filter 90 has a cylindrical shape and is disposed so that its central axis substantially coincides with the axial direction of the housing.

[0059] The gas generating agent 61 is an agent that is ignited by thermal particles generated by the transfer charge 59 when the igniter 40 is activated, and burns to generate gas. A non-azide gas generating agent is preferably used as the gas generating agent 61, and the gas generating agent 61 is generally formed as a molded body containing a fuel, an oxidizer, and an additive.

[0060] The fuel may be, for example, a triazole derivative, a tetrazole derivative, a guanidine derivative, an azodicarbonamide derivative, a hydrazine derivative, or a combination thereof. Specifically, nitroguanidine, guanidine nitrate, cyanoguanidine, 5-aminotetrazole, or the like is preferably used.

[0061] Examples of oxidizing agents that can be used include basic metal nitrates such as basic copper nitrate, basic metal carbonates such as basic copper carbonate, perchlorates such as ammonium perchlorate and potassium perchlorate, and nitrates containing cations selected from alkali metals, alkaline earth metals, transition metals, and ammonia. Suitable nitrates include sodium nitrate and potassium nitrate.

[0062] Examples of additives include binders, slag formers, and combustion modifiers. Suitable binders include organic binders such as polyvinyl alcohol, metal salts of carboxymethyl cellulose, and stearates, as well as inorganic binders such as synthetic hydrotalcite and acid clay. Other suitable binders include polysaccharide derivatives such as hydroxyethyl cellulose, hydroxypropyl methyl cellulose, cellulose acetate, cellulose propionate, cellulose acetate butyrate, nitrocellulose, microcrystalline cellulose, guar gum, polyvinylpyrrolidone, polyacrylamide, and starch, as well as inorganic binders such as molybdenum disulfide, talc, bentonite, diatomaceous earth, kaolin, and alumina. Suitable slag formers include silicon nitride, silica, and acid clay. Suitable combustion modifiers include metal oxides, ferrosilicon, activated carbon, and graphite.

[0063] The shape of the molded body of gas generating agent 61 may be various, including granular, pellet-like, cylindrical, or other particulate shapes, and disc-like shapes. Furthermore, for cylindrical molded bodies, perforated molded bodies having through holes inside the molded body (for example, a single-hole cylindrical shape or a multi-hole cylindrical shape) are also used. These shapes are preferably selected as appropriate depending on the specifications of the airbag device into which disk-shaped gas generator 100 is incorporated, and it is preferable to select an optimal shape depending on the specifications, such as selecting a shape in which the gas generation rate changes over time when gas generating agent 61 is burned. Furthermore, in addition to the shape of gas generating agent 61, it is preferable to select the size and filling amount of the molded body as appropriate, taking into consideration the burning rate, pressure exponent, etc. of gas generating agent 61.

[0064] The filter 90 can be made of, for example, metal wire such as stainless steel or iron, wound and sintered, or a mesh of woven metal wires pressed together. Specific examples of mesh materials that can be used include knitted wire mesh, plain woven wire mesh, and an aggregate of crimped metal wires.

[0065] Alternatively, a perforated metal sheet wound around the filter 90 may be used. Examples of perforated metal sheets include expanded metal, which is a metal sheet with staggered cuts and then expanded to form holes and form a mesh, and hook metal, which is a metal sheet with holes drilled and flattened by crushing any burrs that may form around the holes. The size and shape of the holes can be varied as needed, and holes of different sizes and shapes may be included in the same metal sheet. Suitable metal sheets include mild steel and stainless steel, as well as non-ferrous metal sheets such as aluminum, copper, titanium, nickel, and alloys thereof.

[0066] The filter 90 functions as a cooling means for cooling the gas generated in the combustion chamber 60 by removing the high-temperature heat of the gas as the gas passes through the filter 90, and also functions as a removal means for removing residue (slag) and the like contained in the gas. Therefore, in order to sufficiently cool the gas and prevent the residue from being released to the outside, it is necessary to ensure that the gas generated in the combustion chamber 60 passes through the filter 90. The filter 90 is disposed at a distance from the peripheral wall portions 12, 22 of the lower shell 10 and the peripheral wall portion 22 of the upper shell 20 that constitute the peripheral wall portions of the housing so that a gap 28 of a predetermined size is formed between the filter 90 and the peripheral wall portions 12, 22.

[0067] A plurality of gas outlets 23 are provided in the peripheral wall 22 of the upper shell 20 in a portion facing the filter 90. The plurality of gas outlets 23 are for directing the gas that has passed through the filter 90 to the outside of the housing.

[0068] Additionally, a metal sealing tape 24 is attached to the inner peripheral surface of the peripheral wall portion 22 of the upper shell 20 as a sealing member to close the plurality of gas ejection ports 23. As this sealing tape 24, an aluminum foil with an adhesive member applied to one side can be suitably used, and the sealing tape 24 ensures the airtightness of the combustion chamber 60.

[0069] A lower support member 70 is disposed in the vicinity of the end of the combustion chamber 60 that is located on the bottom plate portion 11 side. The lower support member 70 has an annular shape and is disposed substantially between the filter 90 and the bottom plate portion 11 so as to cover the boundary between the filter 90 and the bottom plate portion 11. As a result, the lower support member 70 is positioned between the bottom plate portion 11 and the gas generating agent 61 in the vicinity of the end of the combustion chamber 60.

[0070] The lower support member 70 has an annular plate-shaped base portion 71 that is fitted to the bottom plate portion 11 so as to fit along the inner bottom surface of the bottom plate portion 11, an abutting portion 72 that abuts against the inner peripheral surface of the filter 90 closer to the bottom plate portion 11, and a tubular upright portion 73 that stands from the base portion 71 toward the top plate portion 21. The abutting portion 72 extends from the outer edge of the base portion 71, and the upright portion 73 extends from the inner edge of the base portion 71. The upright portion 73 covers the outer peripheral surface of the protruding tubular portion 13 of the lower shell 10 and the outer peripheral surface of the inner covering portion 31 of the holding portion 30 via the extension portion 53 of the cup-shaped member 50.

[0071] The lower support member 70 is a member for fixing the filter 90 to the housing, and also functions as an outflow prevention means for preventing gas generated in the combustion chamber 60 from flowing out through the gap between the lower end of the filter 90 and the bottom plate portion 11 without passing through the inside of the filter 90 when the igniter 40 is activated. For this reason, the lower support member 70 is formed, for example, by pressing a metal plate-shaped member, and is preferably made of a member made of a steel plate such as ordinary steel or special steel (for example, a cold-rolled steel plate or a stainless steel plate).

[0072] An upper support member 80 is disposed at the end of the combustion chamber 60 that is located on the top plate portion 21 side. The upper support member 80 has a substantially disk-like shape, and is disposed between the filter 90 and the top plate portion 21 so as to cover the boundary between the filter 90 and the top plate portion 21. As a result, the upper support member 80 is positioned near the end of the combustion chamber 60, between the top plate portion 21 and the gas generating agent 61.

[0073] The upper support member 80 has a base 81 that abuts against the top plate 21, and an abutment portion 82 that stands upright from the periphery of the base 81. The abutment portion 82 abuts against the inner circumferential surface of the axial end portion of the filter 90 that is located on the top plate 21 side.

[0074] The upper support member 80 is a member for fixing the filter 90 to the housing, and also functions as an outflow prevention means for preventing gas generated in the combustion chamber 60 from flowing out through the gap between the upper end of the filter 90 and the top plate portion 21 without passing through the inside of the filter 90 when the igniter 40 is activated. For this reason, the upper support member 80 is formed, for example, by pressing a metal plate-shaped member, and is preferably made of a member made of a steel plate such as ordinary steel or special steel (for example, a cold-rolled steel plate or a stainless steel plate).

[0075] A disk-shaped cushion material 85 is disposed inside the upper support member 80 so as to come into contact with the gas generating agent 61 accommodated in the combustion chamber 60. As a result, the cushion material 85 is positioned between the top plate portion 21 and the gas generating agent 61 in the portion of the combustion chamber 60 on the top plate portion 21 side, and presses the gas generating agent 61 toward the bottom plate portion 11 side.

[0076] The cushioning material 85 is provided for the purpose of preventing the gas generating agent 61, which is made of a molded body, from being crushed by vibration or the like, and is preferably made of a material such as a ceramic fiber molded body, rock wool, foamed resin (for example, foamed silicone, foamed polypropylene, foamed polyethylene, foamed urethane, etc.), or rubber such as chloroprene and EPDM.

[0077] The top plate portion 21 is flat, and the thickness direction of the top plate portion 21 substantially coincides with the thickness direction of the flat plate portion 16. The flange portion 25 protrudes outward from the end portion of the peripheral wall portion 22 opposite to the top plate portion 21 side. The flange portion 25 is flat, and the thickness direction of the flange portion 25 substantially coincides with the thickness direction of the top plate portion 21.

[0078] In this embodiment, the distance L1 from the outer surface of the top plate 21 to the surface of the flange 25 on the side opposite to the top plate 21 in the axial direction of the housing is 25 mm. The distance L2 from the outer surface of the top plate 21 to the outer surface of the flat plate 16 in the axial direction of the housing is 50 mm. The outer diameter L3 of the peripheral wall 22 is 60.5 mm.

[0079] 2, the flange portion 25 has a substantially rectangular shape when viewed in the axial direction of the housing. Near the corners of the flange portion 25, through-holes 26 are formed to pass through the flange portion 25.

[0080] In this embodiment, the width L4 of the flange portion 25 is 80 mm, and the distance L5 between the two through holes 26 is 68 mm.

[0081] As shown in FIG. 3, in this embodiment, the thicknesses (wall thicknesses) of the flat plate portion 16 and the curved portion 17 are 1.1 mm. The thicknesses (wall thicknesses) of the peripheral wall portion 12 and the curved portion connecting the peripheral wall portion 12 and the flat plate portion 16 are 1.0 mm. The thickness (wall thickness) of the side wall portion of the protruding tubular portion 13 extending from the curved portion 17 toward the upper shell 20 is 1.0 mm, the thickness (wall thickness) of the bottom portion is 0.9 mm, and the thickness (wall thickness) of the curved portion connecting the side wall portion and the bottom portion is 0.85 mm. The thickness (wall thickness) of the top plate portion 21 is 1.0 mm. The thickness (wall thickness) of the peripheral wall portion 22 and the curved portion connecting the top plate portion 21 and the peripheral wall portion 22 is 0.9 mm.

[0082] Thus, in this embodiment, the thickness (1.1 mm) of the flat portion 16 and the curved portion 17 is 1.1 times or more the thickness (1.0 mm, 0.9 mm, 0.85 mm) of the portions of the lower shell 10 other than the flat portion 16 and the curved portion 17. Furthermore, the maximum thickness (1.1 mm) of the lower shell 10 is 1.2 times or more the minimum thickness (0.85 mm) of the lower shell 10. Furthermore, the thickness (1.1 mm) of the flat portion 16 and the curved portion 17 is 0.2 mm or more greater than the thickness (0.9 mm, 0.85 mm) of the portions of the lower shell 10 other than the flat portion 16 and the curved portion 17. Furthermore, the maximum thickness of the lower shell 10 is 1.1 mm or more, and the minimum thickness of the lower shell 10 is 0.9 mm or less. The thickness (1.0 mm) of the top plate portion 21 is at least 0.9 times the thickness (1.1 mm) of the flat plate portion 16 and the curved portion 17. The difference between the maximum thickness (1.1 mm) of the lower shell 10 and the maximum thickness (1.0 mm) of the upper shell 20 is 0.1 mm or less.

[0083] In this embodiment, the tensile strength of the material forming the lower shell 10 and the material forming the upper shell 20 is 780 MPa or more. The mass of the lower shell 10 is 80 g or less. The mass of the upper shell 20 is 62 g or less. The total mass of the lower shell 10 and the upper shell 20 is 142 g or less.

[0084] In a gas generator according to a comparative example, when the pressure inside the housing increased due to combustion of the gas generating agent, the pressure was actually measured and was found to be a maximum of 18.5 MPa in a high temperature environment. Therefore, in the present embodiment, a safety factor of at least two is ensured and the thickness is set as described above so that the rupture pressure at which lower shell 10 ruptures is 37 MPa or higher. Furthermore, when disc-type gas generator 100 is mounted on a vehicle or the like, the thickness is set as described above so that the rupture pressure at which upper shell 20 ruptures is greater than the rupture pressure at which lower shell 10 ruptures, so that even in the case where the housing ruptures due to an increase in pressure inside the housing, lower shell 10 ruptures before upper shell 20 located on the driver's side of the vehicle.

[0085] As shown in Fig. 4, when the gas generating agent 61 is not burning, the pressure inside the housing does not increase, so the housing does not deform and no stress concentration occurs in the housing. On the other hand, as shown in Fig. 5, when the gas generating agent 61 burns and generates gas, the pressure inside the housing increases, so the housing deforms and stress concentration occurs in the housing. Specifically, stress concentrates on the flat plate portion 16, the curved portion 17, and the top plate portion 21. For example, stress is likely to concentrate in the cross-hatched portions of the flat plate portion 16, the curved portion 17, and the top plate portion 21 shown in Fig. 5.

[0086] Next, with reference to FIG. 1, a procedure for assembling disk-shaped gas generator 100 in this embodiment will be described.

[0087] First, the igniter 40 is fixed to the lower shell 10 by injection molding the retaining portion 30, which is made of a resin molded portion. Then, the side wall portion 52 of the cup-shaped member 50, which contains the transfer charge 59, is press-fitted into the retaining portion 30 of the lower shell 10 to fix it. Next, the lower support member 70 is placed on the tip portion 54 of the extension portion 53 of the cup-shaped member 50, and the filter 90 is inserted and positioned toward the inner bottom surface of the lower shell 10.

[0088] Gas generating agent 61 is then filled inside filter 90, and upper support member 80 with cushioning material 85 therebetween is inserted into the upper end portion of filter 90. Thereafter, upper shell 20, with gas ejection port 23 closed with sealing tape 24, is placed over lower shell 10, and lower shell 10 and upper shell 20 are welded together. This completes the assembly of disc-type gas generator 100 having the structure shown in FIG. 1 .

[0089] Here, in disk-shaped gas generator 100 of the present embodiment, no opening is provided in cup-shaped member 50, and therefore the step of filling transfer charge 59 into transfer chamber 57 provided inside cup-shaped member 50 can be carried out very easily. This is because cup-shaped member 50 itself is made of a fragile member with low mechanical strength so that a part of the cup-shaped member will rupture, deform or melt when disk-shaped gas generator 100 is activated. In other words, the work of closing the opening provided in the cup-shaped member in order to fill it with transfer charge 59, such as with aluminum tape or a closing plate, which was necessary when a cup-shaped member having an opening was used, is no longer necessary, and the manufacturing process can be greatly simplified.

[0090] Next, with reference to FIG. 1, the operation of disk-shaped gas generator 100 in the present embodiment will be described.

[0091] When a vehicle equipped with disk-shaped gas generator 100 collides, the collision is detected by collision detection means separately provided in the vehicle, and based on this, a control unit separately provided in the vehicle supplies electricity to activate igniter 40. Transfer charge 59 accommodated in transfer chamber 57 is ignited by the flame generated by the activation of igniter 40, and begins to burn.

[0092] At this time, immediately after the igniter 40 is activated, the ignition charge loaded in the ignition section 41 burns rapidly, causing the squib cup of the ignition section 41 to burst, and the heat generated by the rapid combustion of the ignition charge is transmitted to the transfer charge 59 filled in the transfer chamber 57.

[0093] Next, when the thrust reaches the inside of the cup-shaped member 50, the cup-shaped member 50, which is made of a relatively fragile material, explodes, deforms, or melts. This explosion, deformation, or melting of the cup-shaped member 50 occurs later than the ignition of the transfer charge 59 by the heat particles generated by the combustion of the ignition charge. Here, the transfer charge 59 of the cup-shaped member 50 is subjected to the thrust generated by the combustion of the ignition charge and is scattered and dispersed inside the cup-shaped member 50.

[0094] Therefore, the transfer charge 59 located farther from the igniter 40 is also ignited by the thermal particles in a shorter time and begins to burn, which results in a significant increase in pressure and temperature in the space inside the cup-shaped member 50. As a result, the cup-shaped member 50 bursts, deforms, or melts in a shorter time, and a large amount of thermal particles generated by the combustion of the transfer charge 59 flows into the combustion chamber 60 quickly. These thermal particles are not affected by the cushioning material 85 provided in the lower shell 10 and come into contact with the gas generating agent 61 without being deactivated.

[0095] In this way, the transfer charge 59 and a large amount of heat particles generated by the transfer charge 59 flow into the combustion chamber 60, igniting and burning the gas generating agent 61 contained in the combustion chamber 60, generating a large amount of gas. The gas generated in the combustion chamber 60 passes through the inside of the filter 90, and in this process, heat is removed by the filter 90 and the gas is cooled, and slag contained in the gas is removed by the filter 90 and flows into the gap 28.

[0096] Then, as the pressure in the space inside the housing increases due to the combustion of gas generating agent 61, sealing tape 24 that has been closing gas outlet 23 provided in upper shell 20 ruptures, and gas is ejected to the outside of the housing through gas outlet 23. The ejected gas is introduced into the inside of an airbag provided adjacent to disc-shaped gas generator 100, and inflates and deploys the airbag.

[0097] Note that if the cup-shaped member 50 is made of iron or stainless steel, the strength is higher than if the cup-shaped member 50 were made of aluminum. Therefore, the cup-shaped member 50 does not rupture, deform, or melt in the initial stage of combustion of the enhancer charge 59. At this time, the internal pressure of the cup-shaped member 50 increases until a predetermined time has elapsed at which the cup-shaped member ruptures, deforms, or melts. Then, once the internal pressure reaches a certain level, the cup-shaped member 50 ruptures, deforms, or melts. Therefore, by using an iron-based metal material with high mechanical strength, such as iron or stainless steel, for the cup-shaped member 50, the mechanical strength can be increased to sufficiently promote the combustion of the enhancer charge 59 when the cup-shaped member 50 is ruptured, thereby rupturing the cup-shaped member 50. Such an improvement in the mechanical strength of the cup-shaped member 50 can be achieved by increasing its thickness, even when a metal with low strength, such as aluminum, is used. In this case, the thickness is preferably 0.4 mm to 1.5 mm, and more preferably 0.6 mm to 1.2 mm.

[0098] Fig. 6 is a graph showing the hydro pressure applied to lower shell 10 of disk-shaped gas generator 100 of Fig. 1. Fig. 7 is a graph showing the hydro pressure applied to upper shell 20 of disk-shaped gas generator 100 of Fig. 1. Next, with reference to Figs. 6 and 7, the hydro pressure applied to lower shell 10 and upper shell 20 will be described.

[0099] The rupture pressure was measured by placing the disk-type gas generator 100 in a hydroburst tester. The hydroburst test is a hydraulic rupture pressure measurement test performed by welding a dedicated jig with an oil inlet. The rupture pressure is the pressure (hydro pressure) at which the housing ruptures when oil is gradually poured into the housing. As shown in FIG. 6, the rupture pressure of the lower shell 10 was 37.5 MPa. As shown in FIG. 7, the rupture pressure of the upper shell 20 was 46 MPa. Thus, the rupture pressure of the lower shell 10 was 37 MPa or higher, and the rupture pressure of the upper shell 20 was higher than that of the lower shell 10. Note that a tolerance of about 10% is required for the housing thickness, so the rupture pressure of the upper shell 20 was set to be about 20% higher than that of the lower shell 10.

[0100] Fig. 8 is a graph showing the relationship between the thickness of the flat portion in the lower shell of a disk-shaped gas generator and the rupture pressure of the lower shell. Fig. 9 is a graph showing the relationship between the thickness of the curved portion in the lower shell of a disk-shaped gas generator and the rupture pressure of the lower shell. Next, with reference to Figs. 8 and 9, the relationship between the thickness of the flat portion and the rupture pressure of the lower shell, and the relationship between the thickness of the curved portion and the rupture pressure of the lower shell will be described.

[0101] As shown in Figure 8, the thickness of the flat portion was changed and the rupture pressure of the lower shell was measured multiple times, and an approximation line was calculated from the multiple measured values. The housing used here was the same as the housing described above except for the thickness of the flat portion. It was found that if the thickness of the flat portion was 1.1 mm or more, the rupture pressure was 37 MPa or more, and strength was ensured so that rupture would not occur at temperatures below 37 MPa. Furthermore, as shown in Figure 9, the thickness of the curved portion was changed and the rupture pressure of the lower shell was measured multiple times and an approximation line was calculated from the multiple measured values. The housing used here was the same as the housing described above except for the thickness of the curved portion. It was found that if the thickness of the curved portion was 1.1 mm or more, the rupture pressure was 37 MPa or more, and strength was ensured so that rupture would not occur at temperatures below 37 MPa.

[0102] As explained above, disk-shaped gas generator 100 in the above-mentioned embodiment of the present invention has lower shell 10 and upper shell 20, and is equipped with a housing that contains gas generating agent 61 inside, which generates gas by combustion, and igniter 40 that ignites and burns gas generating agent 61, lower shell 10 has bottom plate portion 11 and cylindrical peripheral wall portion 12 extending from the outer peripheral edge of bottom plate portion 11 toward upper shell 20, bottom plate portion 11 has flat plate portion 16 provided around the periphery of the center of bottom plate portion 11, and curved portion 17 that curves inward from the inner peripheral edge of flat plate portion 16 to be positioned toward the upper shell 20, and has protruding tubular portion 13 that protrudes from the center of bottom plate portion 11 toward the upper shell 20, and the thicknesses of flat plate portion 16 and curved portion 17 are 1.1 times or more the thickness of parts of lower shell 10 other than flat plate portion 16 and curved portion 17.

[0103] According to this, the thicknesses of flat plate portion 16 and curved portions 17, where stress is likely to concentrate when gas generating agent 61 burns and the pressure inside the housing increases, are at least 1.1 times the thickness of the portions of lower shell 10 other than flat plate portion 16 and curved portions 17, so that it is possible to prevent the thickness of the portions of lower shell 10 other than flat plate portion 16 and curved portions 17 from becoming unnecessarily thick while suppressing a decrease in the strength of flat plate portion 16 and curved portions 17, and to suppress an increase in the mass of the housing. In other words, disc-shaped gas generator 100 is capable of suppressing an increase in the mass of the housing while suppressing rupture of the housing.

[0104] Furthermore, disk-shaped gas generator 100 in the above-described embodiment of the present invention has lower shell 10 and upper shell 20, a housing that contains gas generating agent 61 that generates gas by combustion, and igniter 40 that ignites and burns gas generating agent 61, lower shell 10 has bottom plate portion 11 and cylindrical peripheral wall portion 12 that extends from the outer peripheral edge of bottom plate portion 11 toward upper shell 20, and the maximum thickness of lower shell 10 is 1.2 times or more the minimum thickness of lower shell 10.

[0105] As a result, the maximum thickness of the lower shell 10 is 1.2 times or more the minimum thickness of the lower shell 10, which prevents a decrease in the strength of the thickest part of the lower shell 10, while preventing the thickness of the thinnest part of the lower shell 10 from becoming unnecessarily thick, thereby preventing an increase in the mass of the housing.

[0106] Furthermore, disk-shaped gas generator 100 in the embodiment of the present invention described above has lower shell 10 and upper shell 20, and is equipped with a housing that contains gas generating agent 61 inside, which generates gas when burned, and igniter 40 that ignites and burns gas generating agent 61, lower shell 10 has bottom plate portion 11 and a cylindrical peripheral wall portion 12 extending from the outer peripheral edge of bottom plate portion 11 toward upper shell 20, bottom plate portion 11 has flat plate portion 16 provided around the periphery of the center of bottom plate portion 11, and curved portion 17 that curves inward from the inner peripheral edge of flat plate portion 16 to be positioned toward the upper shell 20, and has protruding tubular portion 13 that protrudes from the center of bottom plate portion 11 toward the upper shell 20, and the thicknesses of flat plate portion 16 and curved portion 17 are greater by 0.2 mm or more than the thickness of parts of lower shell 10 other than flat plate portion 16 and curved portion 17.

[0107] According to this, the thickness of the flat plate portion 16 and the curved portion 17, where stress is likely to concentrate when the gas generating agent 61 burns and the pressure inside the housing rises, is 0.2 mm or more greater than the thickness of the parts of the lower shell 10 other than the flat plate portion 16 and the curved portion 17, so that it is possible to prevent a decrease in the strength of the flat plate portion 16 and the curved portion 17 while preventing the thickness of the parts of the lower shell 10 other than the flat plate portion 16 and the curved portion 17 from becoming unnecessarily thick, thereby preventing an increase in the mass of the housing.

[0108] Furthermore, disk-shaped gas generator 100 in the above-described embodiment of the present invention has lower shell 10 and upper shell 20, a housing that contains gas generating agent 61 inside, which generates gas when burned, and igniter 40 that ignites and burns gas generating agent 61, lower shell 10 has bottom plate portion 11 and cylindrical peripheral wall portion 12 that extends from the outer peripheral edge of bottom plate portion 11 toward upper shell 20, and lower shell 10 has a maximum thickness of 1.1 mm or more and a minimum thickness of 0.9 mm or less.

[0109] According to this, the maximum thickness of the lower shell 10 is 1.1 mm or more, and the minimum thickness of the lower shell 10 is 0.9 mm or less, so that the strength of the thickest part of the lower shell 10 is prevented from decreasing, while the thickness of the thinnest part of the lower shell 10 is prevented from becoming unnecessarily thick, thereby preventing the mass of the housing from increasing.

[0110] Furthermore, disk-shaped gas generator 100 in the above-described embodiment of the present invention has lower shell 10 and upper shell 20, and is provided with a housing that contains gas generating agent 61 therein that generates gas by combustion, and igniter 40 that ignites and burns gas generating agent 61, lower shell 10 has bottom plate portion 11 and a cylindrical peripheral wall portion 12 that extends from the outer circumferential edge of bottom plate portion 11 toward upper shell 20, and bottom plate portion 11 has a cylindrical peripheral wall portion 12 that is provided around the periphery of the center of bottom plate portion 11. The upper shell 20 has a flat plate portion 16 having a curved portion 17 that curves inward from the inner peripheral edge of the flat plate portion 16 so as to be positioned toward the upper shell 20, and a protruding tubular portion 13 that protrudes toward the upper shell 20 at the center of the bottom plate portion 11, and the upper shell 20 has a top plate portion 21 and a tubular peripheral wall portion 22 that extends from the outer peripheral edge of the top plate portion 21 toward the lower shell 10, and the thickness of the top plate portion 21 is 0.9 times or more the thickness of the flat plate portion 16 and the curved portion 17.

[0111] As a result, the thickness of the top plate portion 21 is 0.9 times or more the thickness of the flat plate portion 16 and the curved portion 17, which prevents the strength of the top plate portion 21 from decreasing, while preventing the thickness of the flat plate portion 16 and the curved portion 17 from becoming unnecessarily thick, thereby preventing the mass of the housing from increasing.

[0112] Furthermore, disk-shaped gas generator 100 in the embodiment of the present invention described above has lower shell 10 and upper shell 20, a housing that contains gas generating agent 61 inside, which generates gas when burned, and igniter 40 that ignites and burns gas generating agent 61, lower shell 10 has bottom plate portion 11 and cylindrical peripheral wall portion 12 extending from the outer peripheral edge of bottom plate portion 11 toward upper shell 20, upper shell 20 has top plate portion 21 and cylindrical peripheral wall portion 22 extending from the outer peripheral edge of top plate portion 21 toward lower shell 10, and the difference in maximum thickness between lower shell 10 and upper shell 20 is 0.1 mm or less.

[0113] As a result, the difference between the maximum thickness of the lower shell 10 and the maximum thickness of the upper shell 20 is 0.1 mm or less, which prevents one of the lower shell 10 and the upper shell 20 from becoming unnecessarily thicker than the other, thereby preventing the mass of the housing from increasing.

[0114] Furthermore, the disk-shaped gas generator 100 in the embodiment of the present invention described above has a lower shell 10 and an upper shell 20, a housing that contains a gas generating agent 61 that generates gas by combustion, and an igniter 40 that ignites and burns the gas generating agent 61, and the tensile strength of the material forming the lower shell 10 and the material forming the upper shell 20 is 780 MPa or more.

[0115] According to this, the tensile strength of the material forming the lower shell 10 and the material forming the upper shell 20 is 780 MPa or more, so it is easy to ensure the strength of the lower shell 10 and the upper shell 20 without increasing the thickness of the lower shell 10 and the upper shell 20. Therefore, it is possible to prevent the lower shell 10 and the upper shell 20 from becoming unnecessarily thick while preventing a decrease in the strength of the lower shell 10 and the upper shell 20, thereby preventing an increase in the mass of the housing.

[0116] Furthermore, disk-shaped gas generator 100 in the above-described embodiment of the present invention has lower shell 10 and upper shell 20, a housing that contains gas generating agent 61 that generates gas when burned, and igniter 40 that ignites and burns gas generating agent 61, and lower shell 10 has a mass of 80 g or less.

[0117] According to this, the mass of the lower shell 10 is 80 g or less, so that the mass of the housing can be prevented from increasing.

[0118] Furthermore, disk-shaped gas generator 100 in the above-described embodiment of the present invention has lower shell 10 and upper shell 20, a housing that contains gas generating agent 61 that generates gas by combustion, and igniter 40 that ignites and burns gas generating agent 61, and upper shell 20 has a mass of 62 g or less.

[0119] According to this, the mass of the upper shell 20 is 62 g or less, so that the mass of the housing can be prevented from increasing.

[0120] Furthermore, the disk-shaped gas generator 100 in the embodiment of the present invention described above has a lower shell 10 and an upper shell 20, and is provided with a housing that contains gas generating agent 61 that generates gas when burned, and an igniter 40 that ignites and burns gas generating agent 61, and the total mass of the lower shell 10 and the upper shell 20 is 142 g or less.

[0121] According to this, the total mass of the lower shell 10 and the upper shell 20 is 142 g or less, so that the mass of the housing can be prevented from increasing.

[0122] In the above-described embodiment, the protruding tubular portion 13 is formed in a substantially cylindrical shape with a bottom, but this is not limiting. For example, the protruding tubular portion does not have to have a bottom. In this case, the holding portion may be formed in a shape that allows it to be fixed to the protruding tubular portion.

[0123] Although the embodiments of the present invention have been described above, they are merely illustrative examples and do not limit the present invention, and the specific configurations and the like can be appropriately modified in design. Furthermore, the actions and effects described in the embodiments of the invention are merely a list of the most preferable actions and effects resulting from the present invention, and the actions and effects of the present invention are not limited to those described in the embodiments of the present invention.

[0124] For example, in disk-shaped gas generator 100 in this embodiment, the gas generation amount may be set to 2.0 mol, but if the gas generation amount is 2.0 mol or less, the internal pressure of the housing of the disk-shaped gas generator can be set to 18.5 MPa or less, and therefore other disk-shaped gas generators with gas generation amounts of 2.0 mol or less can also have a plate thickness design similar to that of disk-shaped gas generator 100.

[0125] Furthermore, even in a disc-shaped gas generator in which the above-mentioned outer diameter L3 or heights L1, L2 are smaller than those of disc-shaped gas generator 100 in this embodiment, the inner pressure-receiving area is reduced and the load on the housing is reduced, so a plate thickness design similar to that of disc-shaped gas generator 100 is possible. [Explanation of symbols]

[0126] 10 Lower side shell 11 Bottom plate part 12 Peripheral wall section 13 Projected cylinder part 14 Recess 15 Opening 16 Flat plate part 17 Curved section 20 Upper side shell 21 Top plate 22 Peripheral wall section 23 Gas outlet 24 Sealing tape 25 flange 26 Through hole 28 Gap 30 Holding part 31 Inner covering part 32 Outer covering part 33 Connecting part 34 Female connector part 40 Igniter 41 Ignition part 42 terminal pins 50 Cup-shaped member 51 Top wall 52 Side wall 53 Extension section 54 Tip 57 Fire transmission room 59 Transfer Charge 60 Combustion chamber 61 Gas Generator 70 Lower support member 71 Base 72 Contact part 73 Standing section 80 Upper support member 81 Base 82 Contact part 85 Cushioning material 90 filters 100 Disk-type gas generator

Claims

1. a housing having a lower shell and an upper shell, and accommodating therein a gas generating agent that generates gas by combustion; an igniter that ignites and burns the gas generating agent, The lower shell has a bottom plate portion and a cylindrical peripheral wall portion extending from an outer peripheral edge portion of the bottom plate portion toward the upper shell side, the bottom plate portion has a flat plate portion provided around a central portion of the bottom plate portion, and a curved portion that curves inward from an inner peripheral edge portion of the flat plate portion to be positioned toward the upper shell side, and a tubular portion that protrudes toward the upper shell side at the central portion of the bottom plate portion, 10. A gas generator according to claim 9, wherein the thickness of said flat plate portion and said curved portion is 1.1 times or more the thickness of a portion of said lower shell other than said flat plate portion and said curved portion.

2. a housing having a lower shell and an upper shell, and accommodating therein a gas generating agent that generates gas by combustion; an igniter that ignites and burns the gas generating agent, The lower shell has a bottom plate portion and a cylindrical peripheral wall portion extending from an outer peripheral edge portion of the bottom plate portion toward the upper shell side, A gas generator characterized in that the maximum thickness of the lower shell is 1.2 times or more the minimum thickness of the lower shell.

3. a housing having a lower shell and an upper shell, and accommodating therein a gas generating agent that generates gas by combustion; an igniter that ignites and burns the gas generating agent, The lower shell has a bottom plate portion and a cylindrical peripheral wall portion extending from an outer peripheral edge portion of the bottom plate portion toward the upper shell side, the bottom plate portion has a flat plate portion provided around a central portion of the bottom plate portion, and a curved portion that curves inward from an inner peripheral edge portion of the flat plate portion to be positioned toward the upper shell side, and a tubular portion that protrudes toward the upper shell side at the central portion of the bottom plate portion, A gas generator characterized in that the thickness of said flat plate portion and said curved portion is greater by 0.2 mm or more than the thickness of a portion of said lower shell other than said flat plate portion and said curved portion.

4. a housing having a lower shell and an upper shell, and accommodating therein a gas generating agent that generates gas by combustion; an igniter that ignites and burns the gas generating agent, The lower shell has a bottom plate portion and a cylindrical peripheral wall portion extending from an outer peripheral edge portion of the bottom plate portion toward the upper shell side, The maximum thickness of the lower shell is 1.1 mm or more, A gas generator characterized in that the minimum thickness of the lower shell is 0.9 mm or less.

5. a housing having a lower shell and an upper shell, and accommodating therein a gas generating agent that generates gas by combustion; an igniter that ignites and burns the gas generating agent, The lower shell has a bottom plate portion and a cylindrical peripheral wall portion extending from an outer peripheral edge portion of the bottom plate portion toward the upper shell side, the bottom plate portion has a flat plate portion provided around a central portion of the bottom plate portion, and a curved portion that curves inward from an inner peripheral edge portion of the flat plate portion to be positioned toward the upper shell side, and a tubular portion that protrudes toward the upper shell side at the central portion of the bottom plate portion, The upper shell has a top plate portion and a cylindrical peripheral wall portion extending from an outer peripheral edge portion of the top plate portion toward the lower shell side, A gas generator characterized in that the thickness of the top plate portion is 0.9 times or more the thickness of the flat plate portion and the curved portion.

6. a housing having a lower shell and an upper shell, and accommodating therein a gas generating agent that generates gas by combustion; an igniter that ignites and burns the gas generating agent, The lower shell has a bottom plate portion and a cylindrical peripheral wall portion extending from an outer peripheral edge portion of the bottom plate portion toward the upper shell side, The upper shell has a top plate portion and a cylindrical peripheral wall portion extending from an outer peripheral edge portion of the top plate portion toward the lower shell side, A gas generator characterized in that the difference between the maximum thickness of the lower shell and the maximum thickness of the upper shell is 0.1 mm or less.

7. 7. The gas generator according to claim 1, wherein the material forming said lower shell and the material forming said upper shell each have a tensile strength of 780 MPa or more.

8. 7. The gas generator according to claim 1, wherein the mass of the lower shell is 80 g or less.

9. 7. The gas generator according to claim 1, wherein the mass of the upper shell is 62 g or less.

10. 7. The gas generator according to claim 1, wherein a total mass of the lower shell and the upper shell is 142 g or less.

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